This two-games-in-one combo was released back in the late 1980s and was designed to be used with the Super Nintendo Entertainment System (SNES) and an actual exercise bike accessory.

Experts are unsure how many of these were actually sold or how many are available for sale for collectors now - but due to its rarity demand is huge.

This one was sold by a seller in Birmingham just before Christmas for £2,050.

What to look out for when buying and selling old video games

BUYING and selling rare video games can be an expensive business. But what do you need to look out for? Here's LoveAntiques' Phil Barton on what you need to know.

Condition is key - Don't be fooled into thinking that you've found a gem if the box is damaged, ripped or worn as its value will be dramatically reduced if this is the case. Nintendo NES and N64 games came in cardboard boxes.

Don't get drawn into a bidding war - Going head-to-head with someone on an auction site can inflate the game price beyond its reasonable valuation - so be careful.

Visit trade fairs - Trade fairs and games markets are great places to find rare and unusual games, and meet fellow traders. Visiting will also give you a chance to inspect the games' condition.

Keep them safe - If you're getting serious about your collection, it can be difficult to keep your games in top condition. Collectors can buy clear plastic cases to help protect them.

Collect and play - Unless the game is sealed and you want it to increase in value, then enjoy your collection as games are meant to be played with!

Hagane, sold for £970, SNES

Sometime games that don't receive much attention when they're first released become classics - meaning their value among collectors rockets.

Hagane was released on the SNES in 1995 and its only in recent years that it has started being sold for hundreds of pounds online, so if you've got it in your attic it might be worth putting it up for sale.

SNES bundle, sold for £690

If you spent your time playing games and not looking at them as an investment, don't worry, you can still make a decent amount of cash by selling your retro consoles and games you no longer want.

This seller sold his SNES and 52 games for £690.

Most of the games are unboxed - but all work - so make sure yours are in decent condition before you try selling them.

What you need to look out for when selling things on eBay

HERE'S what you need to know before you put your stuff on auction:

Always set a reserve price - Starting with a low price will attract bidders but you don't want to accidentally sell your item for less than it's worth.

Watch out for seller's fees - You can list up to 20 things for free every month but there is a 10 per cent charge if you sell - including postage and packaging.

Set the right amount for postage and packaging - The auction site offers set postage fees based on what sellers with similar products charged but these might not be the best option for you. Use the Royal Mail price finder to get an idea of what it will cost you.

Close your auction on Sunday - According to eBay, the website is at its busiest on Sunday evenings so try to end your auction then to get the best price.

Sell stuff for free on other sites - You can avoid eBay's fees altogether by selling your things on classified sites, like Gumtree, Preloved or Facebook Marketplace.